Rotary actuator and bearing support therefor

Abstract

An axial force exerting in the axial direction of a rotary actuator is uniformly applied to a plurality of axially arranged ball bearings of a bearing set to hold inner and outer rings of each ball bearing in optimum position, thereby heightening the rigidity of the bearing set. A waved washer is interposed between the ball bearings and distributes the axial force so as to axially slide the ball bearings. While being slidden to the optimum positions, the ball bearings are bonded for fixing.

We claim: 
     
       1. A rotary actuator comprising: a rotational shaft;   a plurality of bearing sets arranged in spaced relationship along a longitudinal axis of said rotational shaft to support opposite ends of said rational shaft, each of said plurality of bearing sets including an outer ring and an inner ring which are concentric with respect to said rotational shaft, and a plurality of ball bearings interposed between said outer and inner rings;   an elastic member interposed between the respective inner rings of said plurality of bearing sets and having applied thereto a force in an axial direction of said rotational shaft, said elastic member being a substantially circular sinuous washer having a plane in which a plurality of alternate peaks and valleys perpendicularly intersect; and   wherein said plurality of balls bearings are situated interiorly of a housing of said bearing set in the axial direction of said rotational shaft such that, under the application of an axial force, the ball bearings share substantially equally component forces generated by said elastic member.   
     
     
       2. A rotary actuator according to claim 1, wherein said elastic member is a substantially circular sinuous washer having a plane in which a plurality of alternate peaks and valleys perpendicularly intersect. 
     
     
       3. A rotary actuator having a head for recording and reproducing information in a disk device, the rotary actuator comprising: a rotational shaft;   a plurality of bearing sets arranged in spaced relationship along the axis of said rotational shaft to support opposite ends of said rotational shaft, each of said plurality of bearing sets including an outer ring and an inner ring concentric with said rotational shaft, and a plurality of ball bearings interposed between said outer and inner rings and situated in interiorly of a housing;   an elastic member interposed between the respective inner rings of said plurality of bearing sets and having applied thereto a force in the axial direction of said rotational shaft to intervene in one of the sets of outer rings boded to said housing or of the inner rings bonded to said rotational shaft, and   a spacer member of a predetermined thickness intervening in the other set which opposes said one set, said predetermined thickness being of a geometrical dimension to define a gap between said spacer member and the other set, wherein said gap disappears when the axial force exerted on said elastic member reaches a predetermined value.   
     
     
       4. A rotary actuator according to claim 3, wherein said elastic member is a substantially circular sinuous washer having a plane in which a plurality of alternate peaks and valleys perpendicularly intersect. 
     
     
       5. A rotary actuator comprising: a stationary housing;   a rotational shaft;   a plurality of bearing sets arranged in spaced relationship along the axis of said rotational shaft to support said rotational shaft at opposite ends thereof within said housing, each of said plurality of bearing sets including an outer ring and an inner ring which are concentric with said rotational shaft, and a plurality of ball bearings interposed between said outer and inner rings;   a sleeve slidably mounted between said rotational shaft and said inner ring of said ball bearing sets;   an elastic member interposed between the respective inner rings of said plurality of bearing sets for applying thereto a force in the axial direction of said rotational shaft;   wherein said plurality of ball bearing sets are arrayed in the axial direction of said rotational shaft such that, under the application of an axial force, said plurality of ball bearings substantially equally share component forces generated by said elastic member; and   wherein said inner ring of the respective ball bearing sets is bonded to said sleeve while said outer ring of the respective ball bearing sets is bonded to said housing in a state in which said axial force is applied.   
     
     
       6. A rotary actuator according to claim 5, wherein said elastic member intervenes in one of the sets of the outer rings and of the inner rings, a spacer member of a predetermined thickness intervenes in the other set which opposes said one set, said predetermined thickness being of a geometrical dimension permitting a gap between said spacer member and the other set to be zero when the axial force exerted on said elastic member through said one set reaches a predetermined value, and wherein said inner rings are bonded to said rotational shaft and said outer rings are bonded to said housing while said gap is zero. 
     
     
       7. A rotary actuator according to claim 5, wherein said elastic member is a substantially circular sinuous washer having a plane in which a plurality of alternate peaks and valleys perpendicularly intersect. 
     
     
       8. A rotary actuator comprising: a plurality of bearing sets arranged in spaced relationship along the axis of said rotational shaft to support opposite ends of said rotational shaft, each of said plurality of bearing sets including an outer ring and an inner ring which are concentric with said rotational shaft, and a plurality of ball bearings interposed between said outer and inner rings;   an elastic member interposed between the respective inner rings of said plurality of bearing sets and having applied thereto a force in the axial direction of said rotational shaft;   said elastic member intervenes in one of the sets of the outer rings and of the inner rings, a spacer member of a predetermined thickness intervenes in the other set which opposes said one set, said predetermined thickness being of geometrical dimension permitting a gap between said spacer member and the other set to be zero when the axial force exerted on said elastic member through said one set reaches a predetermined value;   said plurality of ball bearings are situated interiorly of a housing of said bearing sets in the axial direction of said rotational shaft such that, under the application of an axial force, the ball bearings share substantially equally component forces generated by said elastic member; and   wherein said inner rings are bonded to said rotational shaft and said outer rings are bonded to said housing while said gap is zero.